Endovascular system for the treatment of stenoses of the carotid and catheter for this system

ABSTRACT

The invention relates to a catheter, in particular for endovascular applications, comprising a long and flexible, hollow, tubular body ( 1 ) having an insertion end ( 4 ) and a connection end ( 3 ) intended to remain outside the body. According to the invention, the catheter comprises in the insertion end ( 4 ) at least two elements ( 9, 12 ) which are expandable/contractible by means of external operation. Said elements are located at a distance from each other, one upstream and the other downstream of a given section of a vessel. With the catheter it is possible to operate in the section comprised between the two expandable elements ( 9, 12 ) and, if necessary, in the intermediate arterial branch which, on account of the two elements ( 9, 12 ) upstream and downstream, will have a zero flow.

This application is the national phase of international application No.PCT/EP99/09295 filed Nov. 30, 1999 which designated the U.S.

DESCRIPTION

The invention relates to a catheter, in particular for endovascularapplications, comprising a long and flexible, hollow, tubular bodyhaving an insertion end and a connection end intended to remain outsidethe body.

In the medical field it is known that there exists the need to carry outsuitable procedures for the treatment of vessels which are obstructed—atleast over part of their diameter—by constrictions, or so-called“stenoses”, arteriosclerotic plaques with or without superimposedthrombi, or the like, in order to restore the complete accessibility andfunctionality thereof. Said stenoses may hinder or even prevent thenormal flow of substances which physiologically pass through thevessels. In particular in the case of the carotid artery, said stenosesmay hinder or even prevent the normal flow of blood towards the organsin the head such as, for example, the brain and the eyes. Said stenosesmay also release fragments of plaque or thrombi with the possibility ofserious embolisms affecting the abovementioned organs.

Normally these types of pathologies are dealt with by means of externalsurgery. Said surgery involves the incision of the skin and theunderlying layers and isolation of the section of artery affected by thestenosis; it also involves clamping the artery itself, which isperformed upstream and downstream of the stenosis so as to block thecirculation temporarily. In particular, in the case of the carotidartery, said clamping is normally performed upstream and downstream ofthe carotid bifurcation, i.e. on the common carotid, on the internalcarotid and on the external carotid. At this point it is envisagedoperating on the section affected by the stenosis using the appropriateprocedures which envisage removal of the obstructing plaque through theopening of the artery section concerned, which is then carefully cleanedand sewn up again directly or by means of application of a prostheticwidening tissue (called “patch”). The surgical method involves, however,closure of the section of the carotid artery operated on withinterruption of the blood flow for a period of time of about 15-30minutes. During this period of time, the flow of blood to the brain iscompensated for by the flow coming from other arteries directed towardsthe brain.

In 10-15% of cases this compensation of the blood flow is not sufficientand, after just 9 minutes of clamping, serious damage to the brain mayoccur. To avoid this, it is necessary to carry out extremely rapidoperations with the risk of imprecision, or apply special devicesconsisting of temporary bridges (or “shunts”) which are applieddownstream of the section of carotid artery which is obstructed. Thesedevices, however, cause an obstruction in the operating zone and maycause complications and, for these reasons, are used only if absolutelynecessary. In order to identify the cases where shunts are required,numerous systems have been developed for monitoring the state of thebrain or the cerebral blood flow. These systems are not devoid of errorsor inaccuracies, so that many surgeons use the method of brainmonitoring while operating on the patient in the conscious state andunder a local, anaesthetic. This method, which is the safest foravoiding brain damage during the operation, has the drawback that itsubjects the patient to a great deal of stress and often is verypainful, in particular in the case of patients with particularanatomical forms (“bull neck”) or who have carotids affected by lesionsor carotid bifurcations which are situated very high in the neck. Theoperation also involves the possibility of damage to the nerves in theneck, in particular in the case of repeated operations or neckssubjected to radiotherapy, with unpleasant post-operative consequences.

In view of the above situation, for several years now there has been theneed to provide a new instrument for therapeutic treatment which allowstreatment of pathologies such as those described or similar pathologies,using procedures which are less invasive or not invasive at all, inorder to reduce as far as possible the risks for the patient, associatedwith a surgical operation. For this purpose, in about the year 1980,Matias was the first person to transfer the techniques of endoluminaldilation of the peripheral arteries to the carotid arteries. Thesetechniques involve positioning a guide wire beyond the stenoses. Acatheter equipped with an inflatable element (commonly called a“balloon”) is then passed along the guide wire and the inflatableelement is expanded in the region of the stenosis in order to dilate it.This method has been successful, but also involves many complicationsdue to thromboses or embolisms.

The results have improved with the use of elements, called “stents”,which consist in tubular shaped meshwork structures which have the taskof supporting the dilated section, holding in place the thrombus andplaque fragments. Despite this, the number of unsuccessful results havestill been high. In order to avoid embolisms during the procedure, guidewires provided with a “balloon” to be applied inside the internalcarotid artery, or a supporting catheter provided with an expandableelement (or “balloon”) to be applied to the common carotid artery, havebeen developed. These methods, however, are unable to prevent possibleembolisms during the endoluminal manoeuvre since they do not provideprotection during the initial stages of insertion of the guide wires(“Teron” method) and moreover they do not exclude the flow towards thebrain through the external carotid artery.

The object of the present invention is therefore that of providing acatheter which is able to overcome these drawbacks by means of occlusionor clamping involving the inflation of expandable elements (or“balloons”) simultaneously inside the common carotid artery and insidethe external carotid artery. This catheter must also have an operatingchannel which allows the stenotic artery sections to be dilated and theappropriate stents to be applied rapidly, sucking then inside the arterysection concerned any embolism-producing material, thereby associatingthe safety of conventional surgery with the advantages of theendoluminal procedures.

The invention therefore has the aim of providing, by means of simple andlow-cost measures, a catheter of the type described initially whichallows:

exclusion of a section of a vessel from the blood flow, in order toblock temporarily the circulation of the substances whichphysiologically pass through them, so as to be able to carry out anytreatment or manoeuvre inside the said vessel section;

the abovementioned isolation and subsequent treatment using procedureswhich are invasive to a minimal degree or not at all, and in particularthe possibility of insertion in loco by means of an extremely smallincision inside an artery situated at a distance (such as, for example,the femoral artery);

elimination of the need for a surgical operation, thereby reducing therisks for the patient, said risks always being associated with treatmentof the invasive type;

treatment of vessel sections which have undergone a previous surgicaloperation and/or reduction of the operating zone also in the case of afirst operation;

provision of an instrument for treatment which is extremely simple touse;

reduction in the duration and the costs of the operation and the periodof hospitalisation and convalescence of the patient, resulting inconsiderable savings in the associated maintenance costs.

The invention achieves the abovementioned objects by means of a catheterof the type described initially, comprising at the insertion end ordistal end, at least two elements which are expandable/contractible bymeans of external operation.

Said expandable/contractible elements may be arranged at a distance fromone another such that one is able to operate upstream and the otherdownstream of a given section of a vessel or two different adjacentvessel sections.

Said expandable/contractible elements may be adapted, with regard totheir diameters in the expanded condition, to the diameters of thevessels inside which they are to be positioned, so as to occlude thementirely and block temporarily the blood circulation in the section orsections concerned.

Said expandable/contractible elements located at the insertion end maybe inflated/deflated by means of supply and discharge ducts provided inthe thickness of the catheter wall. This solution allows the diameter ofthe catheter to be limited, facilitating insertion of the latter, andavoids occupying the internal central luminal duct, or operatingchannel, which is intended to convey the appropriate treatment means.

The catheter may have a hollow tubular shape with a larger initialdiameter provided externally, in particular at the distal end, with afirst inflatable/deflatable element, operation of which is performed viaone of the ducts provided within the thickness of the catheter.

At least one of the other ducts provided within the thickness of thecatheter may extend, over a certain length, into a second section of thecatheter, of smaller diameter, which extends from the distal end of thelarger-diameter section and terminates in a second inflatable/deflatableelement, operation of which is performed via said duct.

The catheter comprises a further duct in the wall thickness, whichemerges at the tip of the entire catheter, namely at the distal end ofthe second smaller-diameter section. This duct has the function ofconveying the guide wire.

The hollow larger-diameter catheter section has a further central ductwith a diameter suitable for conveying treatment means necessary foroperating in the vessel section or sections comprised between the twoinflatable/deflatable elements. Said treatment means may consist inballoon or stent catheters both of the self-expanding type and the typeexpandable by means of inflation, in which case the stent may be locatedat the distal end of an additional catheter of a suitable diameter andintroduced via the central duct of the catheter according to theinvention, so as to reach the vessel section inside which it must beapplied.

The section comprised between the two inflatable/deflatable elements mayhave a length of the order of between a few cm and about 10 cm, i.e.substantially equivalent to the longitudinal extension, for example, ofstenoses in arterial vessels or the like or the section of a main vesselto be occluded and the first section of a bifurcation branch (as in thecase of a common and external carotid), thus blocking any flow in thesecond dividing branch.

For particular applications, the two elements may be provided atdistances different from those indicated above.

The catheter may have a first external larger diameter of the order ofmagnitude of about 12-13 French and in any case preferably not greaterthan 13-14 French (approximately 4 mm), while the second externalsmaller diameter may be of the order of magnitude of about 5 French(approximately 1.5 mm). For particular applications, diameters withmeasurements different from those indicated above may be envisaged.

The catheter may have, in the connection end or proximal end, anend-piece intended to remain outside the patient's body. Said end-piecemay be provided with tubular elements, which are preferably rigid orsemi-rigid, having the function of providing a connection to theindividual ducts.

The catheter according to the present invention may be usedadvantageously in particular in an endovascular system for the treatmentof stenoses of the carotid, in order to isolate an artery section insidewhich a stenosis is present, so as to block temporarily the blood flowinside the said vessel section. Said system may comprise the followingsteps:

positioning of a guide wire so that, when passing in particular insidethe common carotid, its distal end is arranged inside the internalcarotid;

insertion of the catheter on the guide wire, through the respective ductprovided in the thickness of the catheter wall;

positioning of the catheter so that the end of the smaller-diameterextension is arranged, with respect to the direction of the blood flow,in particular in the external carotid and the larger-diameter end isarranged in particular inside the common carotid;

inflation of the two expandable/contractible elements via the tworespective ducts provided in the thickness of the catheter wall;

treatment of the stenosis in the internal carotid by means of insertionof the appropriate instruments for treatment (guides, balloon catheters,stents, aspirators, angioscopic instruments, IVUS, devices forthrombolysis, catheters for angiographic checks, etc.) through thecentral duct;

aspiration through the central duct 2 of possible residues deriving fromcatheter expansion;

deflation of the two expandable/contractible elements via the tworespective ducts provided in the thickness of the catheter wall;

final monitoring;

extraction of the catheter and the guide wire.

All the abovementioned steps may be performed with continuous visualmonitoring, thanks to one of the well-known existing techniques. In thisconnection, the tubular body of the catheter may comprise radiopaquemarkers for locating and identifying the said catheter.

As a result of the series of measures described above it is possible toprovide, using simple and low-cost means, a catheter which allows:

isolation of a section of a vessel so as to prevent temporarily the flowof the substances which physiologically pass through it, so as to beable to carry out any treatment inside this vessel section;

the abovementioned isolation and subsequent treatment using procedureswhich are only slightly invasive or not at all invasive, and inparticular the possibility of insertion in loco by means of an extremelysmall incision situated at a distance (such as for example the femoralartery);

elimination of the need for a surgical operation, thereby reducing therisks for the patient, said risks always being associated with treatmentof the invasive type;

treatment of vessel sections which have undergone previous surgeryand/or reduction of the operating zone also in the case of a firstoperation;

provision of an instrument for treatment which is extremely simple touse;

reduction in the duration and the costs of the operation and the period,of hospitalisation and convalescence of the patient, resulting inconsiderable savings in the associated maintenance costs.

The additional features and any improvements of the invention will bedescribed in the sub-claims.

The characteristic features of the invention and the advantages arisingtherefrom will emerge more clearly from the following detaileddescription of the accompanying figures in which:

FIG. 1 shows a side view in a preferred embodiment of the catheteraccording to the invention;

FIG. 2 shows an enlarged cross-sectional view of the catheter accordingto FIG. 1, along the line I—I, a further catheter being inserted insidethe central duct;

FIG. 3 shows an enlarged longitudinally sectioned view of the catheteraccording to FIG. 1, with the inflatable/deflatable elements in thenon-expanded condition;

FIG. 4 shows a longitudinally sectioned view of a carotid artery, withthe catheter in position and the inflatable/deflatable elements in theexpanded condition.

FIGS. 5 and 6 are longitudinal sectional views as that of FIG. 3,showing two slight different embodiments of the catheter according tothe invention.

With reference to the figures, and at the moment particularly to FIGS.1-4, a catheter according to the invention comprises a long, hollow,flexible tubular body 1. The tubular body 1 may comprise one or moretubular bodies, but in the preferred embodiment it comprises a singletubular element which has a central luminal duct 2 which extends from aconnecting end, known as the proximal end 3, to an insertion or distalend 4.

The tubular body 1 may be made, for example, by means of extrusion of asmall and flexible material such as nylon, polyurethane, urethane,polyethylene, polyvinyl chloride (PVC), polyamides or the like, whichallows the tubular body 1 to bend for easy positioning inside the vesselinside which the said body must be positioned.

The external diameter of the tubular body 1 may be of the order of about10-13 French (about 3-3.9 mm), and in any case preferably not greaterthan 13-14 French (3.9-4.2 mm), but may vary depending on the specificrequirements.

The central luminal duct 2, or operating duct, has a diameter preferablynot greater than 7 French (2.1 mm).

In the proximal end zone 3, the catheter has a connecting end-piece 5which has a diameter greater than that of the tubular body 1 and whichis intended to remain outside the patient's body.

Three ducts 6, 7 and 8, which have substantially the same diameter aseach other, are provided in the thickness of the wall of the tubularbody 1, but, for further applications, a different number of ducts maybe provided, if necessary also with diameters which are different fromeach other.

The first duct 6 extends from the proximal end 3 and emerges inside afirst inflatable/deflatable element 9 which can be actuated by means ofthe duct 6 itself. Said first inflatable/deflatable element is providedin the immediate vicinity of the distal end 4 and basically consists ofa balloon 9 which is applied outside the wall of the tubular body 1 oris formed integrally with the latter. The diameter of said first balloon9 in the expanded condition is such as to fit perfectly the internaldiameter of the vessel for which it is intended, in particular thecommon carotid 10, in order to block temporarily the blood flow.

The second catheter 7 extends from one end to the other of the catheter,including that of the smaller-diameter extension, and forms the channelfor the introduction of a guide wire.

The third duct 8 extends from the proximal end 3 and extends beyond thedistal end 4 by means of an extension 11 with an external diameter whichis considerably smaller than that of the tubular body 1, in particularby about 5 French (approximately 1.5 mm). Said third duct emerges insidea second inflatable/deflatable element 12 located at the distal end ofthe extension 11. Said second element consists of a balloon 12 which isinflatable/deflatable by means of the duct 8 itself and may be appliedto the distal end of the extension 11 or formed integrally therewith.

The diameter of said second balloon 12, in the expanded condition, issuch as to fit perfectly the internal diameter of a vessel inside whichsaid balloon is intended to be applied, in particular the externalcarotid 210, in order to block temporarily the flow of the blood.

The two balloons 9 and 12 are provided at a distance of about 10 cm fromeach other, but may be provided at different distances depending on thespecific requirements.

The balloons 9 and 12, when not inflated, can also be comprised withinthe profile of the catheter portion onto which they are fitted.

The end-piece 5, at the proximal end 3 is provided with small rigid orsemi-rigid pipes 13 for connecting each duct 6, 7 and 8 and theassociated apparatus. Said apparatus may consist, for example, of meansfor inflating/deflating the balloons 9 and 12 by means of the ducts 6and 8 and guide wires passing through the duct 7. The part connectingthe main lumen of the catheter may have a removable valve and a lateralheader.

With particular reference to FIG. 4, this shows a carotid artery in thezone close to the carotid bifurcation 310. The carotid shown has astenosis 14 in the internal carotid section 110. The figure shows indetail the endovascular system for non-invasive treatment of thestenosis 14.

After positioning the catheter in the zone concerned via the femoralartery, with the aid of a guide wire and known observation means, thefirst balloon 9 is arranged inside the common carotid 10, while thesecond balloon 12 is arranged inside the external carotid.

At this point the balloons 9 and 12 are inflated by means of therespective ducts 7 and 8 with the effect of blocking the blood flowflowing from the common carotid and the reflux flow from the externalcarotid and stopping the flow in the internal carotid, the ostium ofwhich remains accessible.

Owing to the interruption of the blood flow, it is possible to operateon the internal carotid, while ensuring that there is no danger ofembolisms being able to reach extremely delicate organs, such as thebrain for example, via the internal carotid 110. Obstruction of theinternal carotid is not necessary because the distal pressure in theregion of the circle of Willis prevents any flow in the direction of thebrain and, therefore, any embolism.

At this point, the actual treatment is performed by means of the centralduct 2 which constitutes an actual operating duct. By means of thisoperating channel, it is possible to introduce without danger a guideinto the internal carotid; the catheters 15 for dilation and applicationof the stent 16 are then introduced. After the vessel section affectedby the stenosis has been dilated and reinforced with the stent in theappropriate manner, aspiration of any waste matter is performed, a checkcarried out by means of angiography or other means, and renewedaspiration performed, if necessary, thereby completing the treatmentprocedure.

This procedure may be easily implemented within safe time periods, alsowith regard to the 10% (ten percent) of cases involving patients whocannot tolerate clamping of the arteries (less than 5 minutes), asdetermined experimentally in normal endolumimal procedures.

The embodiment of FIG. 5 differs from that previously described in thatthe conduct 7 for the guide wire opens out of the tubular body 1 at aportion 20 located between the proximal end 3 and the baloon 9, insteadof extending up to the proximal end 3 of the catheter.

This embodiment makes the procedure for inserting the catheter veryfast.

According to the embodiment shown in FIG. 6, the tubular body 1 does notprovide for a lumen specifically designed for the passage of the guidewire. This means that the conduct 7 for the guide wire is provided onlyin the distal portion of the catheter, and has an opening 21 locatedbetween the baloons 9 and 12. Therefore the guide wire runs within thecentral lumen 2 of the tubular body 1.

This embodiment allows to optimize the space available in the centrallumen 2 of the tubular body 1.

If desired, one end of the balloons 9 can be positioned at the openingof the central duct 2.

Obviously, the invention is not limited to the embodiment and to thescope of treatment described and illustrated hitherto, but may begreatly varied and/or advantageously applied also in contexts differentfrom the one described, without thereby departing from the basicprinciple described above and claimed below.

In particular, the previously described baloons 9 and 12 can be eithercompliant or non-compliant as well as the catheters and/or the baloonscan be coated or uncoated.

The catheter according to the invention is preferably with soft andatraumatic tip and it can optionally have differentiated flexibility.

What is claimed is:
 1. Catheter in particular for endovascularapplications, comprising a long and flexible, hollow, tubular bodyhaving an insertion end and a connection end intended to remain outsidethe body, and at the insertion end, at least two elements which areexpandable/contractible by means of external operation and which arelocated on said tubular body at a fixed distance from each other such asto be able to operate one upstream and the other downstream of a givensection of a vessel, said expandable/contractible elements being adaptedand/or being able to be adapted, with regard to their diameters in theexpanded condition, to the diameters of the vessels inside which theyare intended to be positioned, so as to block temporarily thecirculation inside said vessel section, wherein the two elements locatedat the insertion end are inflatable/deflatable by means of supplying anddischarge ducts which are provided inside the thickness of the catheterwall.
 2. Catheter according to claim 1, wherein the tubular bodyincludes a main body having a first, larger diameter, provided on theoutside with a first one of said elements which is inflatable/deflatableby means of one of the ducts provided in the thickness of the wall, andwherein at least one other of the ducts inside the thickness of the wallextends, after a certain length, into an extension portion of thetubular body having a second, smaller diameter and provided on theoutside with a second one of said elements.
 3. Catheter according toclaim 2, wherein it comprises at least one additional duct for a guidewire in the thickness of the wall, which emerges on the end side of themost distal end of the smaller-diameter extension.
 4. Catheter accordingto claim 3, wherein said duct for the guide wire extends only in thedistal portion of the catheter and has a proximal end opening locatedbetween the inflatable/deflatable elements and.
 5. Catheter according toclaim 1, further comprising a central duct for conveying treatment meansnecessary for operating in the vessel section affected by stenosis. 6.Catheter according to claim 1, wherein the length of the sectioncomprised between the two inflatable/deflatable elements is generally ofthe order of a few centimeters to about 10 cm, substantially equivalentto the stenosis of arterial vessels or the length necessary foroccluding a vascular trunk and an arterial bifurcation branch thereof,blocking the blood flow in the second branch.
 7. Catheter according toclaim 2, wherein the first greater external diameter is of the order ofmagnitude of 12-13 French (about 3.9 mm), preferably not greater than 14French (4.2 mm) while the second smaller diameter is of the order ofmagnitude of 5 French (about 1.5 mm).
 8. Catheter according to claim 1,wherein the connection end has an end-piece which is intended to remainoutside the patient's body, which end-piece is provided with tubularconnection elements connected to the individual ducts.
 9. Catheteraccording to claim 1, used to block the flow, towards the brain, of theinternal carotid artery, inside which the stenosis is present.
 10. Amethod of using a catheter comprising a long and flexible, hollow,tubular body having an insertion end and a connection end intended toremain outside the body, and at the insertion end, at least two elementswhich are expandable/contractible by means of external operation andwhich are located on said tubular body at a fixed distance from eachother such as to be able to operate one upstream and the otherdownstream of a given section of a vessel, said expandable/contractibleelements being adapted and/or being able to be adapted, with regard totheir diameters in the expanded condition, to the diameters of thevessels inside which they are intended to be positioned, so as to blocktemporarily the circulation inside said vessel section, wherein the twoelements located at the insertion end are inflatable/deflatable by meansof supplying and discharge ducts which are provided inside the thicknessof the catheter wall, wherein the tubular body includes a main bodyhaving a first, larger diameter, provided on the outside with a firstone of said elements which is inflatable/deflatable by means of one ofthe ducts provided in the thickness of the wall, wherein at least oneother of the ducts inside the thickness of the wall extends, after acertain length, into an extension portion of the tubular body having asecond, smaller diameter and provided on the outside with a second oneof said elements, and further comprising a central duct for conveyingtreatment means necessary for operating in the vessel section affectedby stenosis, the method comprising the following steps: insertion of thecatheter inside the carotid artery via the femoral artery; positioningof the catheter so that the end of the smaller-diameter extension isarranged, with respect to the direction of the blood flow, in theexternal carotid and the larger-diameter end is arranged inside thecommon carotid; inflation of the two expandable/contractible elementsvia the two respective ducts provided in the thickness of the catheterwall; operation on the stenosis of the internal carotid via insertion ofthe appropriate treatment instruments though the central duct;aspiration through the central duct of possible residues deriving fromcatheter expansion; deflation of the two expandable/contractibleelements via the two respective ducts provided in the thickness of thecatheter wall; final monitoring and extraction of the catheter and theguide wire.
 11. Catheter according to claim 2, wherein said main bodyand said extension portion have a different flexibility.
 12. Catheteraccording to claim 1, wherein the expandable/contractible elements, whennot inflated, are contained within the profile of the tubular body ontowhich they are fitted.
 13. Catheter in particular for endovascularapplications, comprising a long and flexible, hollow, tubular bodyhaving an insertion end and a connection end intended to remain outsidethe body, and at the insertion end at least two elements which areexpandable/contractible by means of external operation and which arelocated at a distance from each other such as to be able to operate oneupstream and the other downstream of a given section of a vessel, saidexpandable/contractible elements being adapted and/or being able to beadapted, with regard to their diameters in the expanded condition, tothe diameters of the vessels inside which they are intended to bepositioned, so as to block temporarily the circulation inside saidvessel section, wherein the two elements located at the insertion endare inflatable/deflatable by means of supplying and discharge ductswhich are provided inside the thickness of the catheter wall, whereinthe tubular body includes a main body having a first, larger diameter,provided on the outside with a first one of said elements which isinflatable/deflatable by means of one of the ducts provided in thethickness of the wall, and an extension portion having a second, smallerdiameter and provided on the outside with a second elements, and furthercomprising at least one additional duct for a guide wire in thethickness of the wall, which emerges on the end side of the most distalend of the smaller-diameter extension, said duct for the guide wireextends only in the distal portion of the catheter and has an openinglocated between the inflatable/deflatable elements.